Digital camera with attitude and shake detection

ABSTRACT

A digital camera with an anti-blur function is provided with simple structures. The digital camera comprises an automatic exposure control mechanism for an automatic exposure mode and inclinometer. As sub-modes, the automatic exposure mode comprises a normal program mode and a high-shutter-speed priority program mode. Output of the inclinometer is repeatedly checked at a predetermined period to detect camera-shake. Camera-shake is determined by stable or unstable output from the inclinometer. When the output is unstable, it is determined that camera-shake exists, and the high-shutter-speed priority program mode is selected. Contrarily, when it is stable, it is determined that no camera-shake exists, and the normal program mode is selected. Attitude of the camera, which is sensed by the inclinometer, is recorded to a detachable PC card with the image data when camera-shake is not detected. If camera-shake is detected, the sensed attitude data is invalidated.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a digital camera.

2. Description of the Related Art

In a digital camera that is capable of recording an image andreproducing a recorded image, a camera is known that detects an attitudeof the camera body from the vertical (which may be classified as thelateral (see FIG. 17) and longitudinal (see FIG. 16) positions of thecamera body). In a recording mode, the above digital camera includesattitude information about the camera body with the image data. In theplayback mode the recorded image may be reproduced and displayed on amonitor of the camera in a direction suitable for watching as a playbackimage. Namely, the topside of the monitor and the top side of theplayback image (original subject image) are made almost identical.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a digital camera with asimple structure which includes an inclinometer to sense camera bodyattitude from the vertical and is able to prevent blurring induced bycamera-shake.

According to the present invention, a digital camera is provided with ananti-blur function. The digital camera comprises an automatic exposurecontrol mechanism, a camera attitude sensing processor, a camera-shakedetecting processor and a selecting control processor.

The automatic exposure control mechanism is performed in an automaticexposure mode. The automatic exposure mode comprises at least twosub-modes, such as a normal program mode and high-shutter-speed priorityprogram mode. The high-shutter-speed priority program mode selectshigher shutter speeds when compared to the normal program mode under thesame photographing conditions. The camera attitude sensing processorsenses an attitude of the camera from the vertical. The camera-shakedetecting processor detects camera-shake in accordance with stability ofthe camera attitude. While the automatic exposure mode is performed, theselecting control processor selects the high-shutter-speed priorityprogram mode when the attitude of the camera is unstable, andcamera-shake is detected by the camera-shake detecting processor. On theother hand, while the automatic exposure mode is selected, the selectingcontrol processor may select the normal program mode when attitude ofthe camera is stable and no camera-shake is detected.

The digital camera preferably comprises a recording processor. Togetherwith image data of a photographed image, the recording processor recordsattitude information in a recording medium, which corresponds to theattitude of the camera when the photograph is taken. While the automaticexposure mode is performed, the selecting control processor invalidatesthe attitude information when the attitude of the camera is unstable,and camera-shake is detected by the camera-shake detecting processor.

Further, while the automatic exposure mode is performed, the selectingcontrol processor may switch selection of the sub-mode from thehigh-shutter-speed priority program mode to the normal program mode whenthe status of attitude sensed by the camera attitude sensing processorchanges from unstable to stable, and no further camera-shake isdetected.

Preferably, the camera attitude sensing processor comprises aninclinometer and the selecting control processor repeatedly checksoutput from the inclinometer at a predetermined period. If the outputwhich corresponds to the attitude of the camera is unstable while theautomatic exposure mode is performed, the attitude infomation isinvalidated.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and advantages of the present invention will be betterunderstood from the following description, with reference to theaccompanying drawings in which:

FIG. 1 is an electric schematic of a digital camera of an embodiment towhich the present invention is applied;

FIG. 2 is an Automatic Exposure (AE) chart representing the program ofan automatic exposure mode of the digital camera;

FIG. 3 is a perspective view from the backside of the digital camera;

FIG. 4 illustrates a structure of an inclinometer mounted on the digitalcamera of the present embodiment by indicating an inside state of theinclinometer when a photographing lens of the digital camera is trainedvertically upward or downward;

FIG. 5 illustrates the structure of the inclinometer mounted on thedigital camera of the present embodiment by indicating an inside stateof the inclinometer when the digital camera is disposed in theupside-down position;

FIG. 6 illustrates structure of the inclinometer mounted on the digitalcamera of the present embodiment by indicating an inside state of theinclinometer when the digital camera is disposed in the firstlongitudinal position;

FIG. 7 illustrates the structure of the inclinometer mounted on thedigital camera of the present embodiment by indicating an inside stateof the inclinometer when the digital camera is disposed in the secondlongitudinal position;

FIG. 8 illustrates the structure of the inclinometer mounted on thedigital camera of the present embodiment by indicating an inside stateof the inclinometer when the digital camera is disposed in the regularor lateral position;

FIG. 9 illustrates electrical structure of switches in the inclinometer,which are comprised of a metallic ball and four conductive elements asshown in FIGS. 4 through 8;

FIG. 10 illustrates the electrical interconnection between terminals ofthe system controller and the switches shown in FIG. 9;

FIG. 11 is a timing chart of a sensing operation at the systemcontroller for sensing the ON/OFF state of the switches in theinclinometer.

FIG. 12 is a flowchart of the control routine, which relates to thepresent embodiment, and is executed in the digital camera;

FIG. 13 is a flowchart of the control routine in a recording mode;

FIG. 14 is a flowchart of the control routine in a playback mode;

FIG. 15 is a flowchart of the control routine when the automaticexposure mode is selected;

FIG. 16 illustrates a photographing operation with the digital cameradisposed in a longitudinal position; and

FIG. 17 illustrates the digital camera disposed in the regular orlateral position, and displaying a reproduced image that wasphotographed in the longitudinal position of FIG. 16, on a monitormounted on the digital camera.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is described below with reference to embodimentsshown in the drawings.

FIG. 3 is a perspective view of a digital camera of the presentembodiment, which is applied to the present invention. A photographinglens 14 is provided on a front side of a camera body 12 of the digitalcamera 10, and on the upper surface of the camera body 12 is a releasebutton 16 and an LCD panel 17. On the LCD panel 17, various informationconcerning the operational status of the camera, photographing, and soon, are indicated.

Further, a laterally long rectangular LCD monitor 18 is provided for thedigital camera 10, on about the center of the backside of the camerabody 12. The LCD monitor 18 is a color display monitor. In the recordingmode, live video of a subject to be monitored through the photographinglens 14 is displayed on the LCD monitor 18. In the playback mode acaptured image is displayed on the LCD monitor 18.

Furthermore, on the backside of the camera body 12, disposed around theLCD monitor 18, a viewfinder 20, mode dial 22 and function buttons 24,are provided. When a power switch (not shown) of the digital camera 10is in ‘ON’ state, the recording mode and playback mode can be selectedby revolving the mode dial 22.

An AE (automatic exposure) control mechanism is mounted on the digitalcamera 10, and by operating the function buttons 24, either a manualexposure mode or AE (automatic exposure) mode can be selected. Assub-modes of the AE mode, either a normal program mode (normal automaticexposure type) or high-shutter-speed priority program mode (high shutterspeed priority automatic exposure type) can be selected. In thehigh-shutter-speed priority program mode, a relatively fast shutterspeed is automatically selected, compared to the shutter speed selectedin the normal program mode with the same conditions. FIG. 2 is aprogrammed AE chart of the AE mode. A broken line A indicates aprogrammed AE line for the normal program mode, and a solid line Bindicates the line for the high-shutter-speed priority program mode.

An inclinometer 50 (refer FIGS. 4-8) is provided for the digital camera10 to sense an attitude of the camera body 12 against the vertical,which may correspond to a lateral or longitudinal position of the camerabody 10. In the recording mode of the digital camera 10, attitudeinformation of the camera body 12, sensed by the inclinometer 50 duringa photographing operation, is recorded along with the image data to amemory in an IC card, such as a PC card 39. In the playback mode, theplayback image is displayed on the LCD monitor 18 in accordance with theattitude information, which is recorded in the memory, so that thetopside of the playback image and the camera body 12 are parallel.

For example, when a subject S is photographed with the camera body 12held in the longitudinal position, as shown in FIG. 16, and the imagedata obtained by the above is reproduced in the playback mode, the imageof the subject S is displayed on the LCD monitor 18 in such manner thatthe topside of the image and the substantial topside of the camera body12 are substantially identical, as shown in FIG. 17.

FIG. 1 is an electrical schematic of the digital camera 10. A systemcontroller 30 which comprises a microcomputer, is provided to thedigital camera 10, and generally controls the digital camera 10. Aphotometric sensor 31, release switch 32 connected with the releasebutton 16, switch group 33 including switches connected with thefunction buttons 24, the LCD panel 17, LCD monitor 18 and inclinometer50 are connected to the system controller 30. Further, an aperture 15,shutter 19, CCD 34, analog signal processor 35, A/D converter 36,digital signal processor 37 and PC card controller 38 are connected tothe system controller 30.

When the release button 16 is depressed, the system controller 30derives the subject brightness via the photometric sensor 31. At thismoment, a subject image formed on the surface of the CCD 34, through thephotographing lens 14, is converted to electrical signals by the CCD 34.The electrical signals are then digitalized via the analog signalprocessor 35 and the A/D converter 36, and input to the digital signalprocessor 37. In the digital processor 37, a predetermined process isapplied to the digitalized signals and image data is generated. Thisimage data is recorded to the PC card 39, which has a built-innon-volatile memory, such as a flash memory (recording medium), forexample.

The PC card 39 is connected with the digital processor 37 via the PCcard controller 38. The digital processor 37 can record image data of acaptured image to the PC card 39 via the PC card controller 38. Further,the digital processor 37 can transfer image data recorded in the PC card39 to the buffer memory 40 via the PC card controller 38.

In the playback mode, image data is transferred from the PC card 39 tothe buffer memory 40 via the digital signal processor 37. In therecording mode, monitoring video (moving video) of the subject imageformed on the surface of the CCD 34 is input to the digital signalprocessor 37 from the A/D converter 36. The image data in each of therecording and playback mode, are output to the LCD monitor 18, anddisplayed on the LCD monitor as playback images.

A description of the inclinometer 50, which senses the attitude of thecamera body 12 is given as follows with reference to FIGS. 4 through 8.The inclinometer 50 is fixed on a printed circuit board 48 (refer FIG.3) disposed inside the camera body 12, so that top, bottom, right andleft side in each figure (FIG. 4 to FIG. 8) correspond to those of thecamera body 12 described in FIG. 3. A first conductive element 51,second conductive element 52, third conductive element 53 and fourthconductive element 54 are arranged in the inclinometer 50, as shown ineach of FIGS. 4 to 8. A conductive bulb or a metallic ball 55 which isat least has a surface comprised of conductive material, is providedinside the space surrounded by the first through fourth conductiveelements. Each conductive element 51-54 is connected to the systemcontroller 30.

When the digital camera 10 is disposed in the lateral position (as shownin FIG. 17), which is a regular position, the metallic ball 55 issettled in the position shown in FIG. 8. As a result, the thirdconductive element 53 and the fourth conductive element 54 areelectrically connected together. When the digital camera 10 is disposedin the first longitudinal position (which is achieved by rotating thecamera body 12, 90 degrees clockwise around the optical axis of thephotographing lens from the regular or lateral position, as shown inFIG. 16), the metallic ball 55 is settled in the position shown in FIG.6. As a result, the second conductive element 52 and the fourthconductive element 54 are electrically connected together.

When the digital camera 10 is disposed in the second longitudinalposition (which is achieved by rotating the camera body 12, 90 degreescounterclockwise around the optical axis of the photographing lens fromthe lateral position), the metallic ball 55 is settled in the positionshown in FIG. 7. As a result, the first conductive element 51 and thethird conductive element 53 are electrically connected together. Whenthe digital camera 10 is disposed in the upside-down position which iscontrary to the above regular lateral position, the metallic ball 55 issettled in the position shown in FIG. 5. As a result, the firstconductive element 51 and the second conductive element 52 areelectrically connected together. Further, when the photographing lens 14of the digital camera 10 is trained vertically up or down, the metallicball 55 settles in a neutral position where the metallic ball 55 isapart from all the conductive elements as shown in FIG. 4. As a result,none of the conductive elements 51-54 are electrically connected.

Namely, as shown in FIG. 9, the inclinometer 50 consists of a firstswitch SW1 comprised of the first and third conductive elements 51, 53,a second switch SW2 comprised of the first and second conductiveelements 51, 52, a third switch SW3 comprised of the second and fourthconductive elements 52, 54, and a fourth switch SW4 comprised of thethird and fourth conductive elements 53, 54. Each of the four switchesSW1-SW4 is individually closed (switched on) when the metallic ball 55contacts the respective pair of conductive elements, and open (switchedoff) when the metallic ball 55 is apart from the conductive elements.

The system controller 30 has four input/output terminals 1, 2, 3 and 4.The first conductive element 51 is connected with terminal 1, the secondconductive element 52 with terminal 2, the third conductive element 53with terminal 3, and the fourth conductive element 54 with terminal 4.FIG. 10 illustrates the connection between terminals 1-4 of the systemcontroller 30 and the first through fourth switches SW1-SW4 of theinclinometer 50.

A timing chart shown in FIG. 11 indicates an example of a sensingoperation at the system controller 30 that senses the ON/OFF state ofeach switch SW1-SW4 in the inclinometer 50. In this example, the systemcontroller 30 regularly feeds a first pulse signal 61 from terminal 2 tothe second conductive element 52, and simultaneously feeds a secondpulse signal 62 from terminal 3 to the third conductive element 53. Dueto the connection between the switches SW1-SW4 and terminals 1-4, asdescribed in FIG. 10, the first pulse signal 61 from terminal 2 is fedto terminal 1 when the switch SW2 is ON, and when the switch SW3 is ON,it is fed to terminal 4. Further, the second pulse signal 62 fromterminal 3 is fed to terminal 1 when the switch SW1 is ON, and when theswitch SW4 is ON, it is fed to terminal 4.

Therefore, the system controller 30 monitors both input signals fromterminals 1 and 4. When the system controller detects the first pulsesignal 61 applied to terminal 2, in terminal 1, it determines that theswitch SW2, which corresponds to the upside-down position, is ON. Whenthe system controller 30 detects the first pulse signal 61 applied toterminal 2, in terminal 4, it determines that the switch SW3, whichcorresponds to the first longitudinal position, is ON. When the systemcontroller 30 detects the second pulse signal 62 applied to terminal 3,in terminal 1, it determines that the switch SW1, which corresponds tothe second longitudinal position, is ON. When the system controller 30detects the second pulse signal 62 applied to terminal 3, in terminal 4,it determines that the switch SW4, which corresponds to the regularlateral position, is ON.

FIG. 12 is a flowchart of a control process, relating to the presentinvention, which is executed by the system controller 30. This controlprocess starts when the power switch of the camera 10 is switched on.First of all, the system controller is initialized, and counters C1through C4, the operation of which are described hereinafter, are reset(Step S1). Subsequently, the selection of the mode dial 22 is checked(Step S3). Then, a determination is made as to whether the PC card 39 isset or not. When it is determined that the PC card 39 is set, therecording mode selection is checked (Step S5, S7). Contrarily, when thePC card 39 is not set, the control proceeds to Step S25.

When the recording mode is selected, an interrupt caused by an intervaltimer is enabled (Step S11). Further, an interrupt caused by a playbacktrigger is disabled and an interrupt caused by a recording trigger isenabled (Step S13 and S15). Subsequently, the control routine returns toStep S3. NOTE: the interrupt, playback triggers and recording triggersare described hereinafter. On the other hand, at Step S7, when it isdetermined that the recording mode is not selected, a determination ismade as to whether the playback mode is selected (Step S17).

If the playback mode is selected, interrupt caused by the interval timeris disabled (Step S19). And then, interrupt caused by the recordingtrigger is disabled and interrupt caused by the playback trigger isenabled (Step S21 and S23). Subsequently, the control returns to StepS3. On the other hand, at Step S17, when it is determined that theplayback mode is not selected, interrupt caused by the interval timer,recording trigger and playback trigger is disabled (Step S25, S27 andS29), and the control routine returns to Step S3.

FIG. 13 is a flowchart of a control routine process (an interrupthandling) in the recording mode. This control routine process startswhen the release switch 32 is switched on (which corresponds to arecording trigger), when the release button 16 is depressed, while therecording mode is selected. The control routine begins with photometryby the photometric sensor 31, and then a determination is made as towhether or not the normal program mode is selected (Step S31 and S33).When the normal program mode is selected, combination of f-number andshutter speed is selected in accordance with the programmed AE line forthe normal program mode, as indicated by the broken line A in FIG. 2(Step S35). And then, the aperture and exposure (shutter speed) arecontrolled in accordance with the selected combination (Step S37 andS39), so that a subject image is formed on the surface of the CCD 34 andis converted to image data.

The image data obtained by the above process is recorded by the memoryprovided in the PC card 39 (Step S41). Subsequently, validity of theattitude information for the camera body 12, which is sensed by theinclinometer 50 during an image capturing operation, is checked (StepS43). If the attitude information is valid, the attitude information isrecorded in the memory of the PC card 39, together with the data of thecaptured image (Step S45). This interrupt handling then ends and thecontrol returns to the main routine. If the attitude information isinvalid, this interrupt handling ends immediately, and the controlreturns to the main routine without executing Step S45.

When it is determined at Step S33 that the normal program mode is notselected, a combination of f-number and shutter speed is selected inaccordance with the programmed AE line of the high-shutter-speedpriority program mode which is indicated by the solid line B in FIG. 2(Step S47). The control then reverts to Step S37 and the processcontinues as previously described i.e., the aperture and exposure(shutter speed) are controlled in accordance with the selectedcombination (Step S37 and S39), so that a subject image formed on thesurface of the CCD 34 is converted to image data, and the Steps 41-45,as described above, are then executed.

FIG. 14 is a flowchart of a control routine process (an interrupthandling) in the playback mode. This control process starts when therelease switch 32 is switched on (which corresponds to a playbacktrigger) by the operation of the release button 16, when the playbackmode is selected. First of all, a check is made to see whether arecorded image is being displayed on the LCD monitor 18 (Step S51). Ifno image is currently being replayed on the LCD monitor 18, image datarecorded in the PC card 39 is transferred to the buffer memory 40 (StepS53), and the transferred image data is fed to the LCD monitor 18, sothat the reproduced or playback image is displayed on the LCD monitor 18(Step S55). The control process in this interrupt handling then returnsto the main routine. Contrarily, when it is determined at Step S51 thata recorded image is reproduced and currently being replayed on the LCDmonitor 18, output of image data to the LCD monitor 18 is suspended(Step S57).

FIG. 15 is a flowchart of a control routine in the AE mode which may becomprised of a normal and high-speed-shutter program mode. This routineis an interrupt handling by the interval timer, and it is periodicallyrepeated while the AE mode is selected.

In the control-flow including this routine, signals from theinclinometer 50 are cyclically checked at a predetermined period whilethe AE mode is selected. If the signals from the inclinometer 50 arestable, the normal program mode is selected and the exposure iscontrolled by the normal program mode. On the other hand, if the outputfrom the inclinometer 50 is unstable, the high-speed-shutter programmode is selected and the exposure is controlled by thehigh-speed-shutter program mode. Although the attitude (the lateral orlongitudinal position) of the camera body 10 is generally fixed, themetallic ball 55 in the inclinometer 50 moves about with cameramovement. This situation occurs when the camera is operated in a movingcar for example, and the image is blurred. When the camera orinclinometer 50 is shaken, the metallic ball 55 bounds about the spacewithin the inclinometer 50 and one of the first through fourth switchesSW1-SW4 is alternately switched between the ON and OFF states. Whenalternation between the ON and OFF states is repeated rapidly, theattitude information is invalidated and treated as void.

The inclinometer 50, which uses contact of a conductive or metallic ballbetween conductive elements, is originally utilized for detecting theattitude of the camera. However the inclinometer 50 can also be utilizedto determine camera-shake by detecting rapid alternate switching betweenthe ON and OFF states, by one of the first to fourth switches SW1-SW4.Therefore, in a camera 10 to which an embodiment of the presentinvention is applied, the inclinometer 50 is utilized not only fordetecting the attitude of the camera but also for detectingcamera-shake. When the detected camera-shake exceeds a predeterminedrapidity, the high-shutter-speed priority program mode is selected andthe automatic exposure mechanism is controlled by the high-shutter-speedpriority program, so that blurring of the photographed image isprevented.

Selection between the normal program mode or the high-shutter-speedprogram mode is described as follows with reference to FIG. 15.

Firstly, whether the first switch SW1 is ON or not, is checked (StepS61). If the first switch SW1 is ON, the counter C1 is incremented byone (Step S63), and each counter C2, C3 and C4 is reset (Step S65). Thecontrol then proceeds to Step S67.

If it is determined at Step S61 that the first switch SW1 of theinclinometer 50 is OFF, whether the second switch SW2 is ON, is checkedat Step S69. If the second switch SW2 is ON, the counter C2 isincremented by one, and each counter C1, C3 and C4 is reset (Step S69,S71 and S73) and the control proceeds to Step 67.

If it is determined at Step S69 that the second switch SW2 of theinclinometer 50 is OFF, whether the third switch SW3 is ON, is checkedat Step S75. If the third switch SW3 is ON, the counter C3 isincremented by one, and each counter C1, C2 and C4 is reset (Step S75,S77 and S79). Subsequently, the control proceeds to Step 67.

If it is determined at Step S75 that the third switch SW3 of theinclinometer 50 is OFF, whether the fourth switch SW4 is ON, is checkedat Step S81. If the fourth switch SW4 is ON, the counter C4 isincremented by one, and each counter C1, C2 and C3 is reset (Step S81,S83 and S85) and the control proceeds to Step 67. If it is determined atStep 81 that the fourth switch SW4 of the inclinometer 50 is OFF,namely, when every first to fourth switch SW1-SW4 is OFF, each of thecounters C1, C2, C3 and C4 is reset concurrently (Step 81 and 87), andthe control proceeds to Step S67.

At Step S67, a determination is made as to whether the counter C1exceeds a predetermined value A (e.g. A=3). If the counter C1 exceedsthe predetermined value A (i.e. when C1 is 4 or more when A=3), theattitude information of the camera body 12, which is sensed by theinclinometer 50 while photographing, is validated and the sub-mode ofthe AE mode is set to the normal program mode (Step S89 and S91). Thecontrol process in this interrupt handling then ends and returns to themain routine.

When it is determined at S67 that the counter C1 is below thepredetermined value A, a determination is then made as to whether thecounter C2 exceeds the predetermined value A (Step S93). If the counterC2 exceeds the predetermined value A, the attitude information of thecamera body 12, which is sensed by the inclinometer 50 whilephotographing, is validated and the sub-mode of the AE mode is set tothe normal program mode (Step S93, S89 and S91). The control of thisinterrupt handling then ends and returns to the main routine.

When it is determined at S93 that the counter C2 is below thepredetermined value A, a determination is then made as to whether thecounter C3 exceeds the predetermined value A (Step S95). If the counterC3 exceeds the predetermined value A, the attitude information of thecamera body 12, which is sensed by the inclinometer 50 whilephotographing, is validated and the sub-mode of the AE mode is set tothe normal program mode (Step S95, S89 and S91). The control in thisinterrupt handling then ends and returns to the main routine.

When it is determined at S95 that the counter C3 is below thepredetermined value A, a determination is then made as to whether thecounter C4 exceeds the predetermined value A (Step S95 and S97). If thecounter C4 exceeds the predetermined value A, the attitude informationof the camera body 12, which is sensed by the inclinometer 50 whilephotographing, is validated and the sub-mode of the AE mode is set tothe normal program mode (Step S97, S89 and S91). The control in thisinterrupt handling then ends and returns to the main routine.

When it is determined at S97 that the counter C4 is below thepredetermined value A, namely, when every counter C1-C4 is below thepredetermined value A, the attitude information of the camera body 12,which is sensed by the inclinometer 50 while photographing, isinvalidated and the sub-mode of the AE mode is set to thehigh-shutter-speed priority program mode (Step S97, S99 and S101). Thecontrol in this interrupt handling then ends and returns to the mainroutine.

As described above, at Step S67, S93, S95 and S97, it is determinedwhether any of the counters C1 through C4 exceed the predetermined valueA. The control-flow shown in FIG. 15 is repeated at a predeterminedperiod, thus if one of the counters C1-C4 exceed the predetermined valueA, it can be determined that the metallic ball 55 has kept one of theswitches SW1-SW4 in an ON state for a certain period. Consequently, itcan be regarded that camera-shake did not exceed a predetermined valuefor the above certain period. Namely, if one of the counters C1-C4exceed the predetermined value A, it is determined that the camera hasbeen stable for the above certain period, which is defined by thepredetermined value A, and the normal program mode is selected as thesub-mode of the AE mode. Contrarily, if none of the counters C1-C4exceed the predetermined value A, it is then determined that the camerais unstable (namely, the camera 10 is shaking), and thehigh-shutter-speed priority program mode is selected as the sub-mode ofthe AE mode. Consequently, image blur is prevented.

Although the embodiments of the present invention have been describedherein with reference to the accompanying drawings, obviously manymodifications and changes may be made by those skilled in this artwithout departing from the scope of the invention.

The present disclosure relates to subject matter contained in JapanesePatent Application No. 2000-023522 (filed on Feb. 1, 2000) which isexpressly incorporated herein, by reference, in their entireties.

1. A digital camera comprising: an automatic exposure control mechanismthat operates in an automatic exposure mode which comprises at least twosub-modes including a normal program mode and a high-shutter-speedpriority program mode, wherein said high-shutter-speed priority programmode selects a higher shutter speed in comparison with said normalprogram mode under a same photographing condition; a camera attitudesensing processor that senses an attitude of said camera with respect tothe vertical; a camera-shake detecting processor that detects acamera-shake in accordance with a stability of said attitude, sensed bysaid camera attitude sensing processor; a selecting control processorthat selects said high-shutter-speed priority program mode as saidsub-mode, when said attitude, sensed by said camera attitude sensingprocessor, is unstable and said camera-shake is detected by saidcamera-shake detecting processor while said automatic exposure mode isperformed; wherein said camera attitude sensing processor comprises aninclinometer, and said selecting control processor repeatedly checksoutput from said inclinometer at a predetermined period and invalidatesattitude information about said attitude detected while photographing ifsaid output corresponding to said attitude is unstable while saidautomatic exposure mode is performed.
 2. A camera according to claim 1that comprises a recording processor which records in a recordingmedium, said attitude information about said attitude detected whilephotographing, together with image data corresponding to an image takenduring said photographing and wherein said selecting control processorinvalidates said attitude information when said attitude, sensed by saidcamera attitude sensing processor, is unstable and said camera-shake isdetected by said camera-shake detecting processor while said automaticexposure mode is performed.
 3. A camera according to claim 1, whereinsaid selecting control processor selects said normal program mode assaid sub-mode, when said attitude sensed by said camera attitude sensingprocessor is stable and said camera-shake is not detected, while saidautomatic exposure mode is performed.
 4. A camera according to claim 1,wherein said selecting control processor switches selection of saidsub-mode from said high-shutter-speed priority program mode to saidnormal program mode when status of said attitude sensed by said cameraattitude sensing processor changes from unstable to stable and saidcamera-shake is no longer detected, while said automatic exposure modeis performed.
 5. A digital camera comprising: an automatic exposurecontrol mechanism that operates in an automatic exposure mode whichcomprises at least two sub-modes including a normal program mode and ahigh-shutter-speed priority program mode, wherein saidhigh-shutter-speed priority program mode selects a higher shutter speedin comparison with said normal program mode under a same photographingcondition; a camera attitude sensing processor that senses an attitudeof said camera with respect to the vertical; a camera-shake detectingprocessor that detects a camera-shake in accordance with a stability ofsaid attitude, sensed by said camera attitude sensing processor; aselecting control processor that selects said high-shutter-speedpriority program mode as said sub-mode, when said attitude, sensed bysaid camera attitude sensing processor, is unstable and saidcamera-shake is detected by said camera-shake detecting processor whilesaid automatic exposure mode is performed; and a recording processorwhich records in a recording medium, attitude information about saidattitude detected while photographing, together with image datacorresponding to an image taken during said photographing and whereinsaid selecting control processor invalidates said attitude informationwhen said attitude, sensed by said camera attitude sensing processor, isunstable and said camera-shake is detected by said camera-shakedetecting processor while said automatic exposure mode is performed.